1. Technical Field
The present disclosure relates to an air conditioner including an outdoor unit and an indoor unit.
2. Related Art
The outdoor unit of the air conditioner includes an outdoor heat exchanger. The outdoor heat exchanger functions as an evaporator in a heating operation performed. When air outside a room (hereinafter described as the outdoor air) is low in temperature, frost may form on the outdoor heat exchanger. The frost having formed on the outdoor heat exchanger during the heating operation is caused to melt in a reverse cycle defrost operation. The melted frost is discharged as drain water to the outside through a bottom plate of the outdoor unit disposed below the outdoor heat exchanger. In the reverse cycle defrost operation, the outdoor heat exchanger is heated by a refrigerant compressed by a compressor to become hot by circulating the refrigerant through the compressor, the outdoor heat exchanger, and an indoor heat exchanger in this order with an outdoor fan stopped. Moreover, the bottom plate of the outdoor unit functions as a drain pan.
If the heating operation is performed at an outdoor air temperature of approximately 0° C., the amount of frost formation is increased. In this case, frost forms not only on the outdoor heat exchanger, but on the outdoor fan for ventilating the outdoor heat exchanger, a bell mouth in the vicinity of the outdoor fan, and the like. It is difficult to melt the frost forming on the outdoor fan and the like in a normal defrost operation that melts the frost forming on the outdoor heat exchanger. Hence, for example, JP-A-2010-121789 proposes an air conditioner that performs a fan defrost operation for removing the frost forming on the outdoor fan and the like. In the fan defrost operation, if the outdoor air temperature is within a predetermined range after the end of the defrost operation that is performed with the outdoor fan stopped, the outdoor fan is rotated at a predetermined number of revolutions for a fixed period of time while the cycle remains reversed in a refrigerant circuit. Consequently, air heated by the outdoor heat exchanger hits against the outdoor fan, the bell mouth, and the like. As a result, the frost forming on the outdoor fan, the bell mouth, and the like can be melted.